An animal model of spontaneous malignant melanoma with many features in common with the human disease is described in the Sinclair Miniature Swine. No comparable model exists for basic studies of melanoma, and this tumor system provides a unique comparative model for improving our understanding of the tumor biology of melanoma. In this research, we propose to: 1. Use chromatographic methods, in particular our newly developed high-performance liquid chromatographic (HPLC) techniques interfaced with mass spectrometry, for the separation, identification and measurement of melanogens in melanoma. 2. Examine urine, plasma, and tissues of normal swine and swine at various stages of melanoma to identify and to measure levels of intermediary metabolites of the melanin synthetic pathway. 3. Assess the significance of selected biologic markers in urine and/or plasma as related to normal swine, swine with known tumor burden, and swine in regression and with recurrent disease. 4. Advance and develop chromatographic methods to expand the range of biologic markers (melanogens) to be separated, identified, and quantitated. 5. Use chromatography and interfaced mass spectrometry to elucidate and confirm the structure of marker molecules; and our long term objective is to relate this research to a better understanding of the biochemistry of human melanoma.